Two new built-in functions: issubclass() and isinstance(). Both take classes as their second arguments. The former takes a class as the first argument and returns true iff first is second, or is a subclass of second. The latter takes any object as the first argument and returns true iff first is an instance of the second, or any subclass of second. Also, change all occurances of pointer compares against PyExc_IndexError with PyErr_ExceptionMatches() calls.